Coil arrangement

Abstract

A coil device (2) has: an element main body (4) containing a magnetic body; a coil portion (6α) provided in the element main body (4); and a terminal electrode (8) connected to a lead portion of the coil portion (6α). A shield layer (10) containing a metal and a resin is formed in at least one face (4a) of the outer surface of the element main body (4).

Description

Technical Field

[0001] The present invention relates to coil devices for applications such as inductors. Background Technology

[0002] Inductors and other coil devices are widely used in electronic devices. In order to reduce the leakage of a portion of the magnetic flux generated by the flow of current to the outside of the product, in the coil device of Patent Document 1, a shield made of copper sheet is formed separately from the component body of the coil device and installed on the component body to block the leakage magnetic flux.

[0003] However, if the shield is formed and installed separately from the component body in this way, there are technical problems that the coil assembly becomes larger and the manufacturing cost of the coil assembly increases.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Publication No. 2019-516246 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] The present invention was made in view of the following actual situation, and its object is to provide a coil device that can effectively reduce leakage flux, especially at high frequencies, and can also achieve miniaturization of the device and reduction of manufacturing costs.

[0009] Means for solving technical problems

[0010] The inventors have conducted specialized research on coil devices that can effectively reduce leakage flux, and can achieve miniaturization and reduced manufacturing costs. As a result, they discovered that by forming a specific shielding layer on the surface of the component body, even if the shielding layer is thin, leakage flux from the coil device can be effectively reduced, especially at high frequencies, and thus the present invention was completed.

[0011] That is, the coil device of the present invention has:

[0012] The main body of the component contains a magnetic material;

[0013] The coil portion is disposed within the main body of the component; and

[0014] Terminal electrodes, which are connected to the lead portion of the coil portion.

[0015] A shielding layer containing metal and resin is formed on at least one side of the outer surface of the component body.

[0016] This shielding layer can be formed simply by coating a paste containing metal and resin, followed by drying and curing, and its thickness can be easily controlled. Therefore, compared to structures where a metal sheet shield is mounted on the component body, the coil device can be manufactured more easily. Furthermore, compared to coil devices with a structure where a metal sheet is mounted on the component body, the fit between the shielding layer and the component body is improved, and the coil device can also be miniaturized.

[0017] Preferably, the shielding layer has a metal-rich region in which the observed metal content is higher than that of the resin. Preferably, the cross-section of the metal-rich region contains more than 50% of the metal. More preferably, the cross-section of the metal-rich region contains more than 80% of the metal. It is also believed that this metal-rich region improves the blocking effect of leakage flux.

[0018] Preferably, the shielding layer has a resin-rich region where a greater amount of the resin is observed, and this resin-rich region exists at the interface between the component body and the metal-rich region. This resin-rich region is believed to improve the adhesion between the shielding layer and the component body.

[0019] Alternatively, the terminal electrode may have a region made of the same material as the metal-rich region of the shielding layer. This configuration allows for effective reduction of leakage flux at specific noise frequencies. This is believed to be because the metal-rich region of the same material can cover a wider area of ​​the component body surface. Furthermore, the terminal electrode and shielding layer can be formed simultaneously from the same raw materials, thus reducing manufacturing costs.

[0020] Preferably, the shielding layer has a coating layer formed by applying a paste containing the metal and the resin to the outer surface of the element body. The coating layer can be easily formed, and its thickness is easy to control. Therefore, compared to coil devices with shielding made of metal sheets, design changes are easier, and manufacturing costs can be reduced.

[0021] Preferably, the shielding layer contains Ag. It has been confirmed that the leakage flux can be effectively reduced, especially at high frequencies, by using a shielding layer containing Ag, even if it is thin.

[0022] Preferably, the paste contains flat-shaped metal powder. Alternatively, the paste may contain spherical metal powder. Furthermore, it is preferable that the coating layer is formed by heat-treating the paste at 170°C to 230°C.

[0023] The shielding layer formed by this paste improves the reduction of leakage flux. Particularly preferred is the presence of small metal powder with an average particle size of 800 nm or less, more preferably 100–500 nm. By including this metal powder, when the paste coating film is heat-treated at a temperature (170°C–230°C) to cure the resin contained in the paste, the metal content in the metal-rich regions can be increased. Because the metal powder particles are fine, it is considered that near-metallic sintering is unlikely to occur at a temperature lower than the melting point of the metal itself.

[0024] Preferably, the shielding layer is formed on the outer surface opposite to the outer surface of the element body on which the terminal electrodes are formed. This allows the coil device with a shielding layer formed on the reverse mounting side to effectively reduce leakage flux from the reverse mounting side. Alternatively, a plating layer may be formed on the surface of the shield. This plating layer can be formed simultaneously with the plating layer formed on the surface of the terminal electrodes of the coil device.

[0025] The shielding layer may also have a reverse mounting side shielding layer formed on the reverse mounting side of the component body, and a grounding conductive portion extending from the reverse mounting side shielding layer through the side of the component body to the vicinity of the mounting side of the component body.

[0026] This configuration allows the shielding layer to be grounded. Therefore, the shielding layer and the ground potential can be made the same. As a result, the shielding layer's ability to block leakage flux is improved. Furthermore, the grounding conductor also functions as a shield for leakage flux on the side of the component body. Moreover, by grounding the grounding conductor, the connection points of the coil assembly are increased even outside the terminal electrodes, thus improving the mounting strength of the coil assembly.

[0027] Alternatively, a recess can be formed on the mounting side of the component body facing the reverse mounting side, and a mounting-side shielding layer can be formed in the recess. With this configuration, other electronic components such as capacitor chips can be placed in the space formed between the recess and the mounting substrate. Furthermore, the shielding layer formed in the recess reduces leakage magnetic flux, thereby preventing adverse effects on the electronic components.

[0028] Alternatively, the shielding layer can be formed to cover the outer surface of the component body, excluding the mounting side. This configuration can further reduce leakage flux.

[0029] Alternatively, the terminal electrodes can be formed in an L-shape from the mounting side of the component body toward the side of the component body. This configuration facilitates the formation of solder fillets when mounted on a substrate or similar object. Attached Figure Description

[0030] Figure 1AThis is a perspective view of a coil device according to one embodiment of the present invention.

[0031] Figure 1B This is a perspective view of a coil device according to another embodiment of the present invention.

[0032] Figure 1C This is a perspective view of a coil device according to another embodiment of the present invention.

[0033] Figure 1D This is a perspective view of a coil device according to another embodiment of the present invention.

[0034] Figure 1E This is a perspective view of a coil device according to another embodiment of the present invention.

[0035] Figure 2A It is a different perspective. Figure 1A A three-dimensional view of the coil device shown.

[0036] Figure 2B It is a different perspective. Figure 1C A three-dimensional view of the coil device shown.

[0037] Figure 3A It is Figure 1A The diagram shows a cross-sectional view along line IIIA-IIIA when the coil assembly is mounted on the substrate.

[0038] Figure 3B It is Figure 1B The diagram shows a cross-sectional view along line IIIB-IIIB when the coil assembly is mounted on the substrate.

[0039] Figure 3C It is Figure 1D The diagram shows a cross-sectional view along line IIIC-IIIC when the coil assembly is mounted on the substrate.

[0040] Figure 4A This is a schematic diagram of an enlarged cross-sectional photograph of the coil device in the embodiment.

[0041] Figure 4B This is a schematic diagram of an enlarged cross-sectional photograph of a coil device according to another embodiment.

[0042] Figure 5 This is a schematic diagram of a device for measuring leakage flux.

[0043] Explanation of reference numerals in the attached figures

[0044] 2, 2a, 2b, 2c... Inductors

[0045] 4...Component body

[0046] 4a……Top surface (reverse mounting side)

[0047] 4b... Bottom surface (mounting side)

[0048] 4c~4f……Side view

[0049] 41...First Core

[0050] 41a……Flange portion

[0051] 41b……Core section

[0052] 41c……Incision area

[0053] 42……Second Core

[0054] 42a...Magnetic particles

[0055] 6α……Coil section

[0056] 6...electric wires

[0057] 6a……lead section

[0058] 61...Remove the electrode section

[0059] 8...Terminal Electrode

[0060] 8a……Grounding terminal electrode

[0061] 10... Shielding layer

[0062] 10a……Reverse installation side shielding layer

[0063] 10b... Grounding Conductor

[0064] 10c...side shielding layer

[0065] 10d……Installation of side shielding layer

[0066] 12...Metal-rich layer (region)

[0067] 14...Resin-rich layer (area)

[0068] 15……plating layer

[0069] 16... Intermediate layer

[0070] 18……Outermost layer

[0071] 20…concave

[0072] 22……Feet

[0073] 30...Substrate

[0074] 32……pads

[0075] 32a……Grounding pad

[0076] 34……Solder

[0077] 36... Other electronic components

[0078] 50... Leakage flux measuring device

[0079] 52……Analytical device

[0080] 54... Detector

[0081] 56……Measurement of plane Detailed Implementation

[0082] The present invention will now be described with reference to the embodiments shown in the accompanying drawings.

[0083] First Implementation Method

[0084] like Figure 1A As shown, the inductor 2 of the coil device according to the first embodiment of the present invention has an element body 4 composed of a generally rectangular parallelepiped (generally hexahedral).

[0085] The component body 4 has an upper surface 4a, a bottom surface 4b located on the opposite side of the upper surface 4a in the Z-axis direction, and four side surfaces 4c to 4f. The dimensions of the component body 4 are not particularly limited. For example, the dimension in the X-axis direction of the component body 4 can be set to 1.2 to 6.5 mm, the dimension in the Y-axis direction can be set to 0.6 to 6.5 mm, and the dimension in the height (Z-axis) direction can be set to 0.5 to 5.0 mm.

[0086] like Figure 1A , Figure 2A and Figure 3A As shown, a pair of terminal electrodes 8 are formed on the bottom surface 4b of the component body 4. The pair of terminal electrodes 8 are opposite to each other in the X-axis direction and are insulated from each other. In the inductor 2 of this embodiment, by connecting these terminal electrodes 8 with... Figure 3A The pads 32 and the like formed on the substrate 30 are connected, thereby enabling connection to external circuits.

[0087] That is, the inductor 2 can be mounted on various substrates 30, such as circuit boards, using bonding components such as solder 34 or conductive adhesive. When mounted on a substrate 30, the bottom surface 4b of the component body 4 becomes the mounting surface, and the terminal electrode 8 and the substrate 30 are joined by bonding components such as solder 34.

[0088] The main body 4 has a coil section 6α inside. This coil section 6α is constructed by winding an electric wire 6, which serves as a conductor, into a coil shape. In this embodiment... Figure 1AIn the coil section 6α, the winding is crosswise, but it can also be normal winding. Alternatively, the wire 6 can be directly wound onto the core section 41b.

[0089] The wire 6 constituting the coil portion 6α is composed of a conductor portion mainly containing copper and an insulating layer covering the outer periphery of the conductor portion. More specifically, the conductor portion is composed of pure copper such as oxygen-free copper or tough pitch copper, phosphor bronze or brass, red copper, beryllium copper, silver-copper alloys, or copper-clad steel wire. On the other hand, the insulating layer only needs to have electrical insulation properties and is not particularly limited. Examples include epoxy resin, acrylic resin, polyurethane, polyimide, polyamide-imide, polyester, nylon, or synthetic resins made by mixing at least two of the above resins. In addition, in this embodiment, as Figure 1A and Figure 3A As shown, wire 6 is a round wire, and the cross-sectional shape of the conductor part is circular.

[0090] like Figure 1A and Figure 3A As shown, the component body 4 of this embodiment has a first core 41 and a second core 42. Both the first core 41 and the second core 42 can be made of pressed powder containing magnetic material and resin.

[0091] The magnetic material contained in each core 41 and 42 can be composed of, for example, ferrite powder or metallic magnetic powder. Examples of ferrite powder include, for example, Ni-Zn ferrite and Mn-Zn ferrite. As for metallic magnetic powder, there are no particular limitations, and examples include, for example, Fe-Ni alloy, Fe-Si alloy, Fe-Co alloy, Fe-Si-Cr alloy, Fe-Si-Al alloy, Fe-containing amorphous alloy, Fe-containing nanocrystalline alloy, and other soft magnetic alloys.

[0092] Furthermore, byproducts may be appropriately added to the aforementioned ferrite powder or metallic magnetic powder. Additionally, the first core 41 and the second core 42 may, for example, be made of the same magnetic material, and the relative permeability μ1 of the first core 41 and the relative permeability μ2 of the second core 42 may be equal. Alternatively, the first core 41 and the second core 42 may be made of magnetic materials of different materials.

[0093] Furthermore, regarding the magnetic material (i.e., ferrite powder or metallic magnetic powder) constituting the first core 41 or the second core 42, its median particle size (D50) can be set to 5 μm to 50 μm. Moreover, the aforementioned magnetic material can also be composed of multiple particle groups with different D50 values. For example, large-particle-size powder with a D50 of 8 μm to 30 μm, medium-particle-size powder with a D50 of 1 μm to 5 μm, and small-particle-size powder with a D50 of 0.3 μm to 0.9 μm can be mixed.

[0094] As mentioned above, when mixing multiple particle groups, there are no particular restrictions on the proportions of large-diameter, medium-diameter, and small-diameter powders. Furthermore, the large-diameter, medium-diameter, and small-diameter powders can be composed entirely of the same material or of different materials. In this way, by using multiple particle groups to form the magnetic material contained in the first core 41 or the second core 42, the filling rate of the magnetic material contained in the component body 4 can be increased. As a result, various characteristics of the inductor 2, such as permeability, eddy current loss, and DC superposition characteristics, are improved.

[0095] Furthermore, the particle size of the magnetic material can be determined by observing the cross-section of the main body 4 of the observation element using a scanning electron microscope (SEM) or a scanning transmission electron microscope (STEM), and then analyzing the obtained cross-sectional photographs using software. In this case, the particle size of the magnetic material is preferably measured by conversion to the equivalent circle diameter.

[0096] Furthermore, when the first core 41 or the second core 42 is composed of metallic magnetic powder, it is preferable that the particles constituting the powder are mutually insulated. As a method of insulation, an example is forming an insulating coating on the particle surface. Examples of insulating coatings include coatings formed from resin or inorganic materials, and oxide coatings formed by oxidizing the particle surface through heat treatment. When the insulating coating is formed from resin or inorganic materials, examples of resins include silicone resin and epoxy resin. Examples of inorganic materials include phosphates such as magnesium phosphate, calcium phosphate, zinc phosphate, and manganese phosphate, silicates such as sodium silicate (water glass), soda-lime glass, borosilicate glass, lead glass, aluminosilicate glass, borate glass, and sulfate glass. By forming an insulating coating, the insulation between particles can be improved, and the withstand voltage of the inductor 2 can be increased.

[0097] Furthermore, there are no particular restrictions on the resins included in the first core 41 and the second core 42. The following can be used: thermosetting resins such as epoxy resin, phenolic resin, melamine resin, urea resin, furan resin, alkyd resin, polyester resin, and dipropylene phthalate resin; or thermoplastic resins such as acrylic resin, polyphenylene sulfide (PPS), polypropylene (PP), and liquid crystal polymer (LCP).

[0098] like Figure 1AAs shown, the first core portion 41 has a flange portion 41a, a core portion 41b, and a cut portion 41c. Four flange portions 41a protrude toward each side 4c to 4f of the component body 4. A coil portion 6α is mounted on the upper surface of the flange portion 41a, supporting the coil portion 6α. Here, two flange portions 41a protruding along the X-axis are designated as first flange portions 41ax, and two flange portions 41a protruding along the Y-axis are designated as second flange portions 41ay. The thickness of the first flange portion 41ax is thinner than the thickness of the second flange portion 41ay, and a space for accommodating a portion of the lead portion 6a exists below the first flange portion 41ax.

[0099] The core portion 41b is located above the flange portion 41a in the Z-axis direction and is integrally formed with the flange portion 41a. Furthermore, the core portion 41b is composed of a generally elliptical cylinder protruding upwards towards the Z-axis and is inserted inside the coil portion 6α. The shape of the core portion 41b is not limited to... Figure 1A and Figure 3A As shown, it can be made into a shape that matches the winding shape of the coil portion 6α. For example, it can be made into a cylindrical or prismatic shape.

[0100] Cutouts 41c are located between the flanges 41a, and four are formed at the four corners of the XY plane. That is, cutouts 41c are formed near the intersections of the sides 4c to 4f of the component body 4. These cutouts 41c serve as passageways for the lead wires 6a extending from the coil portion 6α. Furthermore, during manufacturing, the cutouts 41c also function as passageways for the forming material constituting the second core 42 to flow from the surface side to the back side of the first core 41. Figure 1A In this design, the cut-out portion 41c is cut into a roughly square shape, but its shape is not particularly limited as long as it allows the lead portion 6a and the aforementioned molding material to pass through. For example, the cut-out portion 41c can also be a through hole that passes through the front and back surfaces of the flange portion 41a.

[0101] like Figure 3A As shown, the second core 42 covers the first core 41. More specifically, the second core covers the coil portion 6α and the core portion 41b above the flange portion 41a, and fills the space below the cut-out portion 41c and the first flange portion 41ax. Furthermore, as... Figure 1A As shown, the lower surface of the second flange portion 41ay forms part of the bottom surface 4b of the component body 4, and the second core portion 42 is not filled below the second flange portion 41ay.

[0102] like Figure 1AAs shown, a pair of lead portions 6a are respectively led out from the coil portion 6α along the Y-axis above the first flange portion 41ax. In addition, the pair of lead portions 6a are respectively folded back near the side surface 4c of the component body 4 and extend from the side surface 4c to the side surface 4d below the first flange portion 41ax.

[0103] Here, the height h of the component body 4 in the Z-axis direction from the bottom surface 4b to the first flange portion 41ax (refer to...) Figure 3A The outer diameter of the lead portion 6a is smaller than that of the lead portion 6a. Therefore, below the first flange portion 41ax, most of the lead portion 6a is housed inside the component body 4 (particularly the second core portion 42), and a portion of the outer periphery of the lead portion 6a is exposed on the bottom surface 4b of the component body 4. The lead portions 6a are all composed of wires 6, but the insulating layer present on the outer periphery of the wire 6 is removed at the exposed portion on the bottom surface 4b, exposing the conductor portion of the wire 6. In this embodiment, as... Figure 2A As shown, the part of the conductor portion of the wire 6 that is exposed on the bottom surface 4b is specifically referred to as the electrode removal portion 61.

[0104] In this embodiment, such as Figure 2A As shown, a pair of terminal electrodes 8 are formed such that they cover a pair of extraction electrode portions 61 respectively, and the extraction electrode portions 61 and the terminal electrodes 8 are electrically connected.

[0105] The terminal electrode 8 may also have a resin electrode layer. Alternatively, the terminal electrode 8 may be a laminated structure having a resin electrode layer and other electrode layers. When the terminal electrode 8 is made into a laminated structure, the resin electrode layer is located at the portion that contacts the take-out electrode portion 61, and the other electrode layers are laminated on the outside of the resin electrode layer, that is, on the opposite side of the take-out electrode portion 61.

[0106] Other electrode layers can be single-layered or multi-layered, and their materials are not particularly limited. For example, other electrode layers can be made of metals such as Sn, Au, Ni, Pt, Ag, Pd, or alloys containing at least one of these metal elements, and can be formed by plating or sputtering. In addition, the average thickness of the terminal electrode 8 as a whole is preferably 10 μm to 60 μm, and the average thickness of the resin electrode layer included in the terminal electrode 8 is preferably 10 μm to 50 μm.

[0107] like Figure 1A As shown, in this embodiment, a shielding layer 10 is formed on the upper surface 4a of the component body 4. The shielding layer 10 has a reverse-mounting side shielding layer 10a that is formed throughout the entire upper surface 4a of the component body 4. The reverse-mounting side shielding layer 10a is formed such that it at least covers the coil portion 6α when viewed from above in the Z-axis direction. This reverse-mounting side shielding layer 10a may not be formed throughout the entire upper surface 4a, but it is preferable to cover the upper surface 4a over a large area.

[0108] The shielding layer 10, consisting of the reverse-mounted side shielding layer 10a, is shown in the schematic diagram of its cross-sectional photograph. Figure 4A and Figure 4B As shown, a metal-rich layer 12, which is a metal-rich region, and a resin-rich layer 14, which is a resin-rich region, are present. A plating layer 15 may also be formed on the surface of the metal-rich layer 12.

[0109] The plating layer 15 may, for example, have an intermediate layer 16 and an outermost layer 18. This plating layer 15 is preferably formed simultaneously with the plating layer formed on the surface of the terminal electrode 8, and the outermost layer 18 of the plating layer preferably contains, for example, tin or a tin alloy with excellent wettability to solder. Furthermore, the intermediate layer contains nickel or a nickel alloy, and may be a single layer or a multi-layered film.

[0110] In this embodiment, the resin-rich layer 14 can be observed at the interface between the surface of the second core 42 of the component body 4 and the metal-rich layer 12. A schematic diagram of a cross-sectional photograph of the coil device obtained by SEM is shown below. Figure 4A and Figure 4B In the cross-sectional images obtained by SEM, the resin components and spatial portions are observed as black areas, the metallic components as white areas, and the magnetic particles as gray areas. (See the schematic diagram of the cross-sectional images.) Figure 4A and Figure 4B In the diagram, diagonal lines or white lines represent cross-sections of metal that appear white when observed via SEM, while diagonally crossed dashed lines represent cross-sections of magnetic particles in the second core that appear gray. The black cross-sections in the main body 4 represent resin. Furthermore, diagonally crossed grid-like shadows represent the space outside the shielding layer that appears black when observed via SEM. Additionally, the black portions inside the main body 4 and shielding layer 10 include some gap spaces in addition to resin components; however, other testing methods (such as sealing tests) confirm that the black portions in the resin-rich layer 14 are resin components, not gap spaces.

[0111] The metal-rich layer 12 can be defined as a layer on the surface of the element body 4 containing magnetic particles 42a, excluding the plating layer 15, in which the area of ​​the white portion representing the metal component is observed to be greater than the area of ​​the black portion representing the resin. Furthermore, the resin-rich layer 14 can be defined as a layer at the interface between the metal-rich layer 12 and the surface of the element body 4, in which the area of ​​the black portion representing the resin is greater than the area of ​​the white portion representing the metal component is observed to be layered.

[0112] In terms of cross-sectional area ratio, the metal content in the metal-rich layer 12 is preferably 50% or more, more preferably 80% or more, and particularly preferably 90% or more. Furthermore, in the resin-rich layer 14, the metal content is preferably 50% or less, more preferably 20% or less, and particularly preferably 3% or less, in terms of cross-sectional area ratio.

[0113] Furthermore, the area occupied by each of the above components can be determined by observing the cross-section using SEM or STEM and performing image analysis on the obtained cross-sectional image. When using SEM, observation based on reflected electron images is preferred; when using STEM, observation based on HAADF images is preferred. In the observed images, the darker areas (nearly black) represent resin components, and the brighter areas (nearly white) represent metallic components.

[0114] The resin-rich layer 14 has a slightly different thickness at the interface between the metal-rich layer 12 and the component body 4, but it is preferably formed continuously. However, the resin-rich layer 14 may also have discontinuous portions along its long side.

[0115] The discontinuous portion is defined as a narrow section where the distance between the metallic component of the metal-rich layer 12 (particles or blocks in the white portion) and the magnetic particles with a diameter of 1 μm or larger contained in the interior of the element body 4 (particles in the gray portion) is less than 0.1 μm. Individual particles with a diameter of less than 0.1 μm are observed, and are not limited to white or gray, but can be included in the resin-rich layer 14 and thus defined.

[0116] The thickness of the resin-rich layer 14 is preferably 0.5 to 5 μm, more preferably 1 to 3 μm. Furthermore, the thickness of the metal-rich layer 12 is preferably 1 to 50 μm, more preferably 3 to 15 μm.

[0117] The metal in the metal-rich layer 12 preferably contains Ag, but may also contain Cu, Ni, Sn, Au, Pd, etc. Furthermore, the resin component in the resin-rich layer 14 is preferably a thermosetting resin such as epoxy resin or phenolic resin.

[0118] Next, the manufacturing method of the inductor 2 in this embodiment will be described.

[0119] First, the first core 41 is manufactured by stamping or injection molding methods such as heat-press forming. In the manufacture of the first core 41, the raw material powder of the magnetic material is mixed with binders, solvents, etc., and granules are formed. These granules are then used as the raw material for molding. In cases where the magnetic material consists of multiple particle groups, magnetic powders with different particle size distributions can be prepared and mixed in a specified ratio.

[0120] Next, a coil portion 6α is mounted on the obtained first core 41. The coil portion 6α can also be a hollow coil into which the wire 6 has been pre-wound into a predetermined shape, and the core portion 41b of the first core 41 is inserted into this hollow coil. Alternatively, the wire 6 can be directly wound around the core portion 41b of the first core 41 to form the coil portion 6α. After combining the first core 41 and the coil portion 6α, as shown... Figure 1AAs shown, a pair of lead wires 6a are drawn from the coil portion 6α and positioned below the first flange portion 41ax.

[0121] Next, the second core 42 is manufactured by insert injection molding. In the manufacture of the second core 42, firstly, the first core 41, which carries the coil portion 6α, is placed inside the molding mold.

[0122] As the raw material constituting the second core 42, a material with fluidity during molding is used. Specifically, a composite material obtained by mixing raw material powder of magnetic material with a binder such as a thermoplastic resin or thermosetting resin is used. Solvents, dispersants, etc. may also be appropriately added to the composite material. In insert injection molding, the above-mentioned composite material is introduced into the molding mold in a slurry state. At this time, the introduced slurry is also filled below the first flange portion 41ax through the cut portion 41c of the first core 41. In addition, during injection molding, it is appropriately heated according to the material of the binder used. In this way, a component body 4 in which the first core 41, the second core 42, and the coil portion 6α are integrated can be obtained.

[0123] Next, a portion of the bottom surface 4b of the main body 4 of the component is... Figure 3A A laser is irradiated at the portion where a pair of terminal electrodes 8 are formed, forming an electrode pre-determining portion. This laser irradiation removes the insulating layer of the lead portion 6a exposed on the bottom surface 4b, forming a take-out electrode portion 61. Furthermore, laser irradiation removes the resin contained in the core portion 42 (and 41) from the outermost surface of the bottom surface 4b. That is, in the electrode pre-determining portion, the magnetic material contained in the core portion 42 (and 41) is exposed, and the take-out electrode portion 61 is exposed. As a result, the terminal electrodes 8 can easily adhere to the bottom surface 4b of the component body 4.

[0124] Next, the resin electrode paste is applied to the predetermined portion of the electrode using a printing method or similar means. The resin electrode paste used at this time contains a binder that forms the resin component and a metal raw material powder that forms the conductor powder. More specifically, the metal raw material powder preferably contains microparticles with a particle size in the micrometer range and nanoparticles with a particle size in the nanometer range.

[0125] Furthermore, at the same time, using the same paste as the resin electrode paste used to form the terminal electrode 8, the paste used for forming... Figure 1A The shielding layer 10 shown is coated with a film formed on the upper surface of the component body 4. The thickness of the coating film can also be the same as the thickness of the resin electrode layer of the terminal electrode 8, but it is preferable to... Figure 4A or Figure 4B The thickness of the metal-rich region 12 after heat treatment is determined to be within the preferred range described above. During coating, the coating process can be repeated multiple times to adjust the thickness, or the coating and drying processes can be repeated.

[0126] After applying resin electrode paste to the electrode pre-determined portion forming the terminal electrode 8 and the shielding pre-determined portion forming the shielding layer 10, the component body 4 is heat-treated under specified conditions to cure the binder (resin component) in the paste. Regarding the heat treatment conditions, for example, it is preferable to set the treatment temperature (holding temperature) to 170°C to 230°C and the holding time to 60 min to 90 min.

[0127] Furthermore, after forming the resin electrode layer that becomes the terminal electrode 8, a plating film or sputtering film can also be appropriately formed on the outer surface of the resin electrode layer. For example, by pre-forming a plating film such as Ni, Cu, or Sn on the outer surface of the resin electrode layer, the wettability relative to solder is improved. When forming the plating film, such as... Figure 4A and Figure 4B As shown, a plating layer 15 is simultaneously formed on the surface of the shielding layer 10.

[0128] By using the above manufacturing method, a pair of terminal electrodes 8 are formed on the bottom surface (mounting side) 4b of the component body 4, and an inductor 2 with a shielding layer 10 formed on the upper surface (reverse mounting side) 4a can be obtained.

[0129] (Summary of the first implementation method)

[0130] Furthermore, in this embodiment, a shielding layer 10 containing metal and resin is formed on at least one side, namely the upper surface 4a, of the outer surface of the component body 4. This shielding layer 10 can be formed simply by coating a paste-like material containing metal and resin and allowing it to dry and cure, making it easy to control the thickness of the shielding layer 10. Therefore, compared to a structure where a metal sheet shield is mounted on the component body, the coil device 2 can be manufactured more easily. Moreover, compared to a coil device where the component body 4 is mounted on a metal sheet, the fit between the shielding layer 10 and the component body 4 is improved, and miniaturization of the coil device 2 is also possible.

[0131] In addition, such as Figure 4A and Figure 4B As shown, the shielding layer 10 has a metal-rich layer 12 in which more metal is observed than resin. Figure 4A The cross-section of the metal-rich layer 12 shown contains more than 50% metal. Furthermore, in... Figure 4B The cross-section of the metal-rich layer 12 shown contains more than 80% metal. It is also believed that the metal-rich layer 12 improves the blocking effect of leakage flux.

[0132] The shielding layer 10 also has a resin-rich layer 14, which exists at the interface between the component body 4 and the metal-rich layer 12. It is believed that the resin-rich layer 14 improves the adhesion between the shielding layer 10 and the component body 4.

[0133] Furthermore, the terminal electrode 8 has a resin electrode layer made of the same material as the metal-rich layer 12 of the shielding layer 10. This configuration allows for effective reduction of leakage flux at specific noise frequencies. This is believed to be because the metal-rich layer 12 of the same material can cover a wider area of ​​the surface of the component body 4. Additionally, the terminal electrode 8 and the shielding layer 10 can be formed simultaneously from the same raw materials, thus reducing manufacturing costs.

[0134] The shielding layer 10 has a coating layer formed by applying a paste containing metal and resin to the outer surface of the component body. The coating layer can be easily formed, and the thickness is easy to control. Therefore, compared with coil devices with shielding made of metal sheets, design changes are easier, and manufacturing costs can be reduced.

[0135] Preferably, the shielding layer contains Ag. Based on the Ag-containing shielding layer, it has been confirmed that even when formed relatively thinly, leakage flux can be effectively reduced, particularly at high frequencies.

[0136] Preferably, the above-mentioned paste contains flat-shaped metal powder. Alternatively, the above-mentioned paste may contain generally spherical metal powder. Furthermore, it is preferable that the above-mentioned coating layer is formed by heat-treating the above-mentioned paste at 170°C to 230°C.

[0137] The shielding layer formed by this paste improves the reduction of leakage flux. Particularly preferred is the presence of small metal powder with an average particle size preferably below 800 nm, more preferably 100–500 nm. By containing this metal powder, the metal content of the metal-rich layer can be increased when the paste coating film is heat-treated at a temperature (170°C–230°C) that allows the resin contained in the paste to cure. Because the metal powder contains nanoparticles, it is considered whether near-metallic sintering occurs at a temperature lower than the melting point of the metal itself.

[0138] In this embodiment, the shielding layer 10 is formed on the upper surface 4a opposite to the bottom surface 4b of the component body 4 on which the terminal electrodes 8 are formed. In this way, the coil device 2 with the shielding layer 10 formed on the reverse mounting side, i.e., the upper surface 4a, can effectively reduce the leakage flux from the reverse mounting side.

[0139] Second Implementation Method

[0140] like Figure 1B and Figure 3B As shown, except as described below, the coil device 2a of this embodiment is the same as the coil device 2 of the first embodiment, and common descriptions are omitted.

[0141] In the coil device 2a of this embodiment, the shielding layer 10 has a reverse-mounting side shielding layer 10a formed on the upper surface 4a of the component body 4, and grounding conductive portions 10b extending from the reverse-mounting side shielding layer 10a through the side surfaces 4c and 4d of the component body 4 to the bottom surface 4b of the component body 4. Each grounding conductive portion 10b is formed approximately at the center of each side surface 4c and 4d of the component body 4 in the X-axis direction, with a width along the X-axis direction that does not short-circuit a pair of terminal electrodes 8, 8, and is connected to the Z-axis. Figure 3B The grounding terminal electrode 8a is connected as shown.

[0142] The grounding terminal electrode 8a is connected to the grounding pad 32a formed on the substrate 30 via connecting members such as solder 34. The grounding terminal electrode 8a is formed in the same way as the terminal electrode 8. In addition, each grounding conductive part 10b is formed in the same way as the reverse mounting side shielding layer 10a.

[0143] In the coil device 2a of this embodiment, the shielding layer 10 can be connected to the grounding pad (ground) 32a of the substrate 30. Therefore, the shielding layer 10 and the grounding potential can be the same. As a result, the shielding layer 10 can improve its ability to block leakage flux. In addition, the grounding conduction portion 10b can also function as a shield for leakage flux on the sides 4c and 4d of the component body 4. Moreover, by grounding the grounding conduction portion 10b, the connection portion of the coil device 2a is increased even in parts other than the terminal electrodes 8 and 8 that supply power to the coil portion 6α, thereby improving the mounting strength of the coil device 2a to the substrate 30.

[0144] Third Implementation Method

[0145] like Figure 1C and Figure 2B As shown, except as described below, the coil device 2b of this embodiment is the same as the coil device 2 or 2a of the above embodiments, and repeated descriptions are omitted.

[0146] In the coil device 2b of this embodiment, the shielding layer 10 has a reverse mounting side shielding layer 10a formed on the upper surface 4a of the element body 4, and side shielding layers 10c extending from the reverse mounting side shielding layer 10a through the four sides of the element body 4 to the bottom surface 4b or near the bottom surface 4b of the element body 4.

[0147] Similar to the reverse-mounted side shielding layer 10a, the side shielding layer 10c is formed continuously with the shielding layer 10a. The lower end of the side shielding layer 10c in the Z-axis direction is formed to be insulated from the terminal electrode 8. Alternatively, the area of ​​the terminal electrode 8 that ensures insulation relative to the lower end of the side shielding layer 10c in the Z-axis direction is formed on the bottom surface 4b of the component body 4.

[0148] Thus, the shielding layer 10 in this embodiment can also be formed to cover the outer surface of the main body of the element, excluding the mounting side, i.e., the bottom surface 4b. With this configuration, leakage flux in the plane (including the plane containing the X and Y axes) direction can also be reduced.

[0149] Fourth Implementation Method

[0150] like Figure 1D and Figure 3C As shown, except as described below, the coil device 2c of this embodiment is the same as the coil device 2 or 2a to 2b of the above embodiments, and repeated descriptions are omitted.

[0151] In the coil device 2c of this embodiment, a recess 20 is formed in the bottom surface 4b of the element body 4, which is recessed in the upward direction toward the Z-axis, between the legs 22, 22 arranged at predetermined intervals along the X-axis. Terminal electrodes 8 are formed on the bottom surface 4b of the legs 22 of the element body 4.

[0152] A mounting-side shielding layer 10d is formed on the top surface of the recess 20 in the component body 4. The mounting-side shielding layer 10d is formed in the same way as the reverse mounting-side shielding layer 10a. It can be formed separately as shown in the figure, or it can be formed continuously by the partial side shielding layers (not shown) formed on the sides 4c and 4d of the component body 4.

[0153] In the coil device 2c of this embodiment, as Figure 3C As shown, other electronic components 36, such as capacitor chips, can be arranged in the space formed between the recess 20 and the mounting substrate 30. In addition, by reducing leakage magnetic flux through the shielding layer 10d formed in the recess 20, adverse effects on the electronic components 36 can also be prevented.

[0154] Fifth Implementation Method

[0155] like Figure 1E As shown, except as described below, the coil device 2d of this embodiment is the same as the coil device 2 or 2a to 2c of the above embodiments, and repeated descriptions are omitted.

[0156] In the coil device 2d of this embodiment, each terminal electrode 8 is formed in an L-shape from the bottom surface 4b of the component body 4 toward each side surface 4e, 4f. In order to ensure insulation from each terminal electrode 8, the shielding layer 10 on the reverse mounting side is not an integral part of the upper surface 4a of the component body 4, but is formed on the upper surface 4a in a manner that separates from each terminal electrode 8 at predetermined intervals in the X-axis direction.

[0157] In the coil device 2d of this embodiment, when installed in Figure 3A When the substrate 30 shown is used, it is easy to form solder fillets and the like on the terminal electrodes 8 formed on the sides 4e and 4f of the component body 4.

[0158] Other implementation methods

[0159] Furthermore, the present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the present invention.

[0160] For example, in the above embodiment, the coil portion 6α is composed of a round wire 6, but the type of wire 6 is not limited to this; it can also be a flat wire with a generally rectangular cross-sectional shape for the conductor portion. Alternatively, it can be a square wire or a stranded wire made by twisting fine wires together. Furthermore, the coil portion 6α can also be constructed by laminating conductive plates.

[0161] In addition, in the above embodiments, as the paste for forming the terminal electrode 8 and the shielding layer 10, a metal raw material powder containing both microparticles and nanoparticles is used, but either one can be used alone, or metal particles with a larger specific surface area than microparticles can be used instead of microparticles.

[0162] Furthermore, in the above-described embodiments, the resin electrode layer of the terminal electrode 8 and the coating film constituting the shielding layer 10 are formed by heat treatment with the same paste, but they can also be different. For example, the terminal electrode 8 is not particularly limited as long as it is an electrode layer that can achieve conductivity with the lead portion 6a of the wire 6.

[0163] In addition, preferably, such as Figure 4B As shown, the metal-rich layer 12 constituting the shielding layer 10 is preferably continuously connected in a layered manner, forming particles or blocks of metal composition. As Figure 4B The paste shown for forming the metal-rich layer 12 is preferably a paste containing metal raw material powders as shown below in a specified proportion.

[0164] That is, the preferred metal raw material powder comprises microparticles with a particle size in the micrometer range and nanoparticles with a particle size in the nanometer range. Regarding the microparticles, the average particle size is preferably 1 μm to 10 μm, more preferably 3 μm to 5 μm. On the other hand, regarding the nanoparticles, the average particle size is preferably less than 800 nm, more preferably 100 nm to 500 nm.

[0165] Furthermore, both microparticles and nanoparticles are preferably composed primarily of Ag. When the ointment also contains metallic elements other than Ag, the form in which these metallic elements exist is not particularly limited. For example, metallic elements other than Ag can exist as particles other than microparticles and nanoparticles, or they can be dissolved in the microparticles.

[0166] In addition, in the above embodiment, a shielding layer 10 is formed on the surface of the element body 4, which is made of resin containing magnetic powder, by a coating method. However, the shielding layer 10 may also be formed on the surface of the element body, which is made of sintered body containing magnetic powder that does not contain resin.

[0167] For example, the first core 41 constituting the main body 4 can also be a sintered body of ferrite powder or metallic magnetic powder. Alternatively, the main body 4 itself can be an FT-type, ET-type, EI-type, UU-type, EE-type, EER-type, UI-type, drum-type, pot-type, or cup-type pressed powder core or sintered core, and a coil can be wound on this core to form an inductor element. In this case, the lead portion does not need to be embedded inside the main body of the element, and can be led out along the outer periphery of the core to connect to the outer surface of the terminal electrode 8.

[0168] Furthermore, the coil device of the present invention is not limited to an inductor, but can also be an electronic component such as a transformer, a choke coil, or a common-mode filter.

[0169] Example

[0170] The present invention will now be described with reference to more detailed embodiments, but the present invention is not limited to these embodiments.

[0171] Example 1

[0172] In Example 1, the fabrication Figure 1A The inductor sample shown. Specifically, the component body 4 is fabricated using the method described in the embodiment, and a shielding layer 10 is formed on the upper surface 4a of the component body 4.

[0173] The shielding layer 10 is formed using the paste shown in the embodiment, and heat treatment is performed under the conditions described in the embodiment.

[0174] like Figure 5 As shown, the obtained inductor sample (coil device 2) is connected to the test substrate 30, and the leakage flux of the sample of coil device 2 is measured by the analysis device 52 of the leakage flux measuring device 50.

[0175] Specifically, on the sample of coil device 2, assuming a measurement plane 56, the detector 54 is moved parallel to the substrate 30 along the measurement plane at specified intervals (e.g., 1 mm) to measure the leakage flux of the sample of coil device 2. The leakage flux test of coil device 2 was conducted under two conditions: 400 kHz (condition 1) and 2 MHz (condition 2). The leakage flux in the vertical direction (Z-axis) and the horizontal direction (XY-axis) was measured for coil device 2. The results are shown in Table 1.

[0176] Table 1

[0177]

[0178] Furthermore, a schematic diagram of the cross-sectional photograph obtained by SEM of the coil device including the shielding layer 10 is shown below. Figure 4AThe average thickness of the metal-rich layer 10 is 15 μm, and the average thickness of the resin layer 14 is 2 μm. Additionally, an intermediate layer 16 composed of nickel plating and an outermost layer 18 composed of tin plating are also observed. Furthermore, the metal content in the metal-rich layer 10, as determined from cross-sectional photographs, is shown in Table 1.

[0179] Example 2

[0180] In Example 2, except as shown below, an inductor sample of the coil device 2 was fabricated in the same manner as in Example 1, and the same measurements were performed. The results are shown in Table 1. Additionally, a schematic diagram of a cross-sectional photograph including the shielding layer 10 is shown in... Figure 4B .

[0181] In Example 2, when forming the sealing layer 10, a paste containing metal powder with an average particle size smaller than that of metal powder in Example 1 was used, and heat treatment was performed under the conditions described in the embodiment.

[0182] Comparative Example 1

[0183] In Comparative Example 1, except that the shielding layer 10 was not formed, an inductor sample of the coil device 2 was fabricated in the same manner as in Example 1, and the same measurements were performed as in Example 1. The results are shown in Table 1.

[0184] evaluate

[0185] As shown in Table 1, compared with Comparative Example 1, it can be confirmed in Example 1 and preferably Example 2 that even with a thinner shielding layer, leakage flux can be effectively reduced, especially at high frequencies. Furthermore, in Examples 1 and 2, the shielding layer 10 can be formed simultaneously with the terminal electrodes, thus enabling miniaturization of the coil device and reduction in manufacturing costs.

[0186] Furthermore, peel-off tests confirmed that, similar to the terminal electrode 8, the shielding layer 10 also exhibits excellent adhesion to the surface of the component body 4. That is, it can be confirmed that... Figure 4A and Figure 4B The black portion at the interface between the surface of the component body 4 and the metal-rich layer 12 shown is not a gap, but can be identified as a resin-rich layer 14 filled with resin.

Claims

1. A coil device, wherein, have: The main body of the component contains a magnetic material; A coil portion is disposed within the main body of the component; and Terminal electrodes, which are connected to the lead portion of the coil portion. A shielding layer containing metal and resin is formed on at least one side of the outer surface of the component body. The shielding layer has metal-rich regions and resin-rich regions. The metal-rich regions are areas where the observed amount of metal is greater than the amount of resin, and the resin-rich regions are areas where the observed amount of resin is greater than the amount of metal. The resin-rich regions exist at the interface between the component body and the metal-rich regions. The metal is a generally spherical or flat metal powder. The shielding layer has a coating layer formed by applying a paste containing the metal and the resin to the outer surface of the component body. On the surface of the coating layer, a plating layer is formed separately from the coating layer. The shielding layer has a reverse mounting side shielding layer formed on the reverse mounting side of the component body. The reverse-mounted shielding layer and terminal electrodes are made of the same material and include the resin and Ag constituting the metal. The thickness of the metal-rich region is 3μm to 15μm.

2. The coil device according to claim 1, wherein, The cross-section of the metal-rich region contains more than 50% of the metal.

3. The coil device according to claim 2, wherein, The cross-section of the metal-rich region contains more than 80% of the metal.

4. The coil device according to any one of claims 1 to 3, wherein, The coating layer is formed by heat-treating the paste at 170°C to 230°C.

5. The coil device according to any one of claims 1 to 3, wherein, The paste contains approximately spherical metal powder.

6. The coil device according to any one of claims 1 to 3, wherein, The paste contains flat-shaped metal powder.

7. The coil device according to any one of claims 1 to 3, wherein, The shielding layer is formed on the outer surface opposite to the outer surface of the element body on which the terminal electrodes are formed.

8. The coil device according to any one of claims 1 to 3, wherein, The shielding layer has: The shielding layer extends from the reverse mounting side through the side of the component body to the grounding conductor near the mounting side of the component body.

9. The coil device according to any one of claims 1 to 3, wherein, A recess is formed on the mounting side of the component body facing the reverse mounting side, and a mounting side shielding layer is formed in the recess.

10. The coil device according to any one of claims 1 to 3, wherein, The shielding layer is formed to cover the outer surface of the main body of the component, excluding the mounting side.

11. The coil device according to any one of claims 1 to 3, wherein, The terminal electrode is formed in an L-shape from the mounting side of the component body toward the side of the component body.

12. The coil device according to claim 6, wherein, The powder contains nanoparticles with an average particle size of 100–500 nm.

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